Switching assembly



Feb. 5, 1963 A. J. KoDA swITcHING ASSEMBLY Filed Feb. 8, 1960 JNVENToR.ARTHUR J. Kom BY @0MM/Mmm,

Zzz/e/n mc( Wg ArroeA/E-a/s `3,038,976, are mounted adjacent UnitedStates Patent Oiilice aware Fired Feb. s, 1ero, ser. No. 7,157 13Claims. (Cr. zoo- 93) This invention relates to a switching means and,more particularly, to a new and improved switching means using a sealedswitch unit.

In sealed switch units or" the type in which a magnetic armaturecontained in a sealed dielectric envelope is a1- ternately moved from acenter-stable position into engagement with a pair of spaced magneticterminals, the operate and release current margins of a winding foroperating the sealed switch unit are often adjusted by the use ofpermanent magnetic biasing means. In singleside-stable switch units, acylindrical permanent magnet is secured to each of the pair of magneticterminals to extend perpendicularly ou-tward therefrom, and thesemagnets are then adjusted so that the terminals are biased to oppositepolarities by fields of unequal intensity. The magnetic armature isnormally held in engagement with one of the terminals by the greaterintensity field to provide a break contact, and the relative intensitiesof the fields produced by the two permanent magnets are adjusted toestablish the desired operate or release currents yfor the winding.However, this biasing arrangement requires the use of two permanentmagnets, and the strength and the positioning of these magnets alsoproduces large stray fields that interfere with the operate and releasecurrent adjustments of adjacent switch units in a plurality unitassembly.

This interaction between the stray fields of the sealed switch units ina plural unit assembly is reduced by alternating the polarities of thebiasing means for adjacent switch units in the manner shown Iin detailin the copend- -ing application of Arthur l. Koda, Serial No. 787,536,tiled January 19, 1959, now Patent No. 3,026,390. However, inapplcations in which a shielding can is not used with the switchingassembly and the individual switch units are positioned immediatelyadjacent each other, as when a plurality of printed circuit relays ofthe type shown in the copending application of Arthur I. Koda, SerialNo. 731,390, filed April 28, 1958, now Patent No.

each other, the interaction between the biasing magnets becomesappreciable. Dichten, Ir. Patent No. 2,245,391 discloses a center'stable relay that is polarized by a single biasing magnet bridged or-disposed between a pair of magnetic terminals. However, thisconstruction cannot be used in single-side-stable relays and does notpermit an accurate adjustment of operate or release currents because thebiasing magnet -must normally saturate both of the magnetic terminals.

Accordingly, an object of lthe present invention is to provide a new andimproved sealed switch unit.

Another object is to provide a switching assembly in which magneticinteraction between the biasing means for adjacent switch units isprevented.

A `further object is to provide a sealed switch unit including new andimproved permanent magnetic biasing means.

Another object is to provide a sealed switch unit including a singlebasing permanent magnet mounted adjacent one magnetic terminal of theswitching unit and spaced `from another magnetic terminal thereof.

A further object is to provide a magnetically biased sealed switch unitin which a permanent magnet having a magnetic axis is positionedadjacent one magnetic terminal and extends toward another magneticterminal with the axis of the permanent magnet forming an acute angle3,076,878 Patented Feb. 5, 1963 relative to a line passing through thetwo magnetic terminals.

A further object is to provide a sealed switch unit in which a singlebiasing magnet longer than the distance between a pair of generallyparallel magnetic terminals is positioned with one pole -face of thepermanent magnet disposed adjacent one magnetic terminal and with anopposite pole face spaced from the other magnetic terminal.

A still further object is to provide a switching `assembly in which twoparallel magnetic terminals of a sealed switch unit engage oppositesides of a `dielectric panel and in which a permanent biasing magnet isdisposed adjacent one of the terminals and is spaced from the other ofthe terminals by the panel.

A Ifurther object is to provide a switching assembly including new andimproved means for mounting a sealed switch unit and a winding thereforon a printed circuit panel.

In accordance with these and many other objects, an embodiment of theinvention comprises a dielectric panel having a plurality of spacedopenings and carrying a plurality of discrete electrically conductivelayers forming a printed circuit pattern. The sealed switch units thatare to be mounted on the printed circuit board each comprise anelongated and generally cylindrical dielectric envelope having a commonterminal extending from one end thereof and a pair of spaced andgenerally parallel magnetic terminals extending lfrom the other endthereof. Each of the dielectric envelopes slidably supports a windingfor moving a center stable magnetic armature contained within theenvelope into alternate engagement with the inner `ends of the pair ofmagnetic terminals. An assembled switch unit and operating winding isinserted into each of the openings in the printed circuit board so thatthe engagement of the terminals with the board and the enwith the edgesof the opening properly locates the Wlnding and switch unit relative toeach other and to the board. In this position, one of -the magneticterminals engages one side of the board and the other of the magneticterminals engages the other side of the board at a location laterally-or transversely offset from the one magnetic terminal. One or more ofthe terminals is suitably secured to the conductive segments toelectrically and mechanically connect the switch units to the printedcircuit pattern.

In order to provide means for magnetically biasing the center stablearmature into normal engagement with one of the magnetic terminals so asto provide a single-sidestable switching construction, each of thesealed switch units is provided with a permanent biasing magnet,preferably rectangular in contiguration, that includes a definitemagnetic axis terminating at the opposite ends of the magnet in a pairof pole faces of opposite polarity. The length of the magnet measuredalong its magnetic axis preferably is greater than the spacing betweenthe pair of magnetic terminals. Each of the permanent magnets extendinggenerally parallel to the printed circuit panel. In this position, themagnetic axis of the biasing magnet forms an acute angle with a linepassing through the two magnetic terminals, and the other pole face isspaced from the other magnetic terminal. The interposition of theprinted circuit panel between the magnet and the other magnetic terminalserves to maintain a fixed separation between the other pole face andthe other magnetic terminal.

With the biasing magnet arranged in .this manner, the inner end of theterminal adjacent the biasing magnet provides a eld of greater intensityso that the adjacent end of the center-stable magnetic armature isnormally held in engagement with this magnetic terminal. Since thelength of the permanent magnet in the direction of its magnetic axis ispreferably greater than the separation between the parallel magneticterminals and since the other pole face of the biasing magnet is spacedfrom the other magnetic terminal, the inner end of this other terminalprovides a magnetic eld of lesser intensity that does not move thearmature away from the more strongly biased terminal. By suitablyadjusting the magnetic iield intensity of the biasing magnet and theseparation between the other magnetic terminal and the spaced pole face,the opera-te or release current of the switching'unit is adjusted to adesired value. Further, by the elimination of one biasing magnet andbecause of the fact that the stray flux ield of the single biasingmagnet is reduced in intensity, the magnetic interaction betweenadjacent switch units on the same printed circuit panel or on adjacentprinted circuit panels is substantially eliminated. Y

Many other objects and advantages of the present invention will becomeapparent from considering the following detailed description inconjunction with the drawings in which:

FIG. l is a top plan view in partial section of a printed circuit relayembodying the present invention which illustrates an assembly of asealed switch unit and a winding in different manners; j

K'FIG. 2 is a sectional view taken along line 2-72 in FIG. l;

FIG. 3 is a sectional view taken along line 3-#3 in FIG. l assuming thata complete switching assembly is shown therein; and

FIG. 4 is a fragmentary perspective view illustrating the relativepositions of a biasing magnet and the magnetic terminals of a sealedswitch unit.

v Referring now more specifically to FIG. l ofthe drawings, therein isshown a switching assembly, indicated generally as 10, which includes adielectric panel 12 deiining a plurality of spaced openings 14 andcarrying a printed circuit pattern comprising a plurality of individualconductive segments or layers 16. lA sealed switch unit 18 slidablysupporting an individual operating winding 20 is disposed in each of theopenings 14 with one or more of the terminals of each of the sealedswitch units 1:8 engaging and soldered to portions of the printedcircuit pattern. The openings 14 conform to the configurations of thewindings and thus serve to locate these windings in a proper positionrelative to the sealed switch units 18.

In order to provide means for rendering each of the vswitching units 18single-side-stable so that a movable armature normally engages one of apair of magnetic terminals, each of the sealed switch units 18 isprovided with a biasing means comprising a single permanent magnet 22.Each of the magnets 22 provides a denite magnetic axis terminating atopposite ends of the magnet 22 vin pole faces of opposite polarity.|'l`he magnets 22 are mounted on one side of the board or panel 12 withone of the pole faces disposed adjacent one of the magnetic terminals onthe switching units 18 and with the magnetic axis extending generallyparallel to the dielectric panel 12. Thus, the other pole faces of themagnets 22 are spaced from the other magnetic terminals by interveningportions kof the dielectric panel 12. Because of this disposition of thepermanent magnets 22, one of the magnetic terminals of each of thesealed switch units 18 is biased with a eld of a particular polaritythat is of greater intensity so that the armature is normally held inengagement with this terminal while the other terminal is biased to anopposite polarity by a field of lesser intensity. By adjusting theposition of the spaced magnetic terminal relative to the permanentmagnet 22 and by adjusting the strength of the magnet 22, the operate orrelease currents of the windings 20 can be adjusted to a desired value.Further, the stray flux eld due to the ysingle biasing magnet 22associated with each ofthe switching units 18 is so small that themagnetic interaction between sealed switch units 18 on the panel 12 orbetween sealed switch units 18 on adjacent panels 12 is prevented.

Referring now more specifically to the dielectric panel or board 12,this panel is formed of any suitable dielectric material and is providedwith a printed circuit pattern on one or both sides thereof by any ofthe methods or processes well known in the art. The printed circuitpattern consists of the plurality of discrete segments or layers 16 ofelectrically conductive material, such as copper. Most of these segmentsinclude an enlarged end portion 16a formed adjacent an edge 12a whichprovides a male connector for interconnecting the switching assembly 10with external circuits. yThe inner ends `o-f most of the segments 16terminate in enlarged portions 16b or 16C of various configurations thatare used to interconnect the components in the switching assembly 1t),such as the sealed switching units 18 or the windings 20, with theprinted circuit pattern. ln the assembly 10 shown in FIG. 1 of thedrawings, the enlarged portions 16h are used, for instance, to extendelectrical connections to the windings 2G, and the enlarged areas 16eare disposed adjacent opposite edges of the elongated openings 14 toprovide means for electrically and mechanically interconnecting theswitching units 18 with the printed circuit pattern. The dielectricpanel 12 also Vincludes a plurality of openings 24 that are u-sed inseof the openings 14 (FIGS.,1 and 2) is provided with a vnarrow opening26 terminating in a circular opening 28.

The sealed switch units 18 can comprise dry type or mercury switchcapsules of any of the types well known in the art. In general, each ofthe sealed switch units 16 includes a sealed dielectric or glassenvelope Si) containing a magnetic and movably mounted armature 32 (FIG.4) that is electrically connected to a terminal or header 34 extendinglfrom the lower end of the envelope 30. A pair o-f generally parallelmagnetic terminals 36 and 38 are carried on the upper end of thedielectric envelope 3i) opposite the terminal 34. The lower ends of theterminals 36 and 38 are offset inwardly toward each other (FIG. 4) toprovide contacts into which the upper end of the armature 32 isalternately moved into engagement under the control of the flux fieldprovided by the winding 2li.

Since the magnetic armature 32 is center-stable, i.e., is normallyspaced midway between the lower ends of the magnetic terminals 36 and38, the biasing magnet 22 is provided to render the sealed switchingunit 1S single-side-stable. ln this condition, the free end of thearmature 32 is normally held in engagement with the lower end of theterminal 3b spaced from the terminal 36. When a llux field of a properorientation is generated by the associated winding 20, the armature ismoved out of engagement with the terminal 3S, which provides a breakcontact, and into engagement with ythe lower end of the terminal 36,which provides a make contact. The termination of the energization ofthe related winding 2h permits the armature 32 to be restored to itsnormal position engaging the terminal pin 3S by the ux 4field providedby the permanent magnet 22.

To accomplish this, the permanent magnet 22 preferably is formed' of arectangular configuration and is provided with a definite magnetic axisor eld orientaltion such that two pole faces 22a and 22h of `oppositepolarities are provided at opposite ends of the magnetic axis. Thelength of the magnet 22 in the direction of the magnetic axis preferablyis longer than the distance separating the terminals 36 and 38. Toprovide a relatively stron-g ux field of a given polarity adjacent thelower end of the break terminal 33, one of the pole faces, such as theface 22a, is disposed immediately adportion of the magnetic terminal 38,and this magnet is adjusted -so that its magnetic axis forms an acuteangle with. a line passing through the magnetic terminals 36 and 38transverse to their axes. Because of the angular displacement of themagnetic axis o-f the magnet 22 and because of the fact that the lengthof this magnet preferably is greater than the distance between theterminal pins 36 and 38, the second pole face of lopposite polarity,such as the pole face 22b, is spaced from the make terminal 36. Becauseof the high reluctance air gap separating the terminal pin 36 from thepole face 22h, the intensity of the field provided by the biasing magnet22 at the lower end of the terminal 38 is substantially greater than theintensity of the magnetic eld of opposite polarity induced at the lowerend of the terminal pin 36. The perjaeent the outer or upper -manentmagnet 22 is preferably Iformed of a material,

such as Alnico V, so that the `field of the permanent magnet 22 isconcentrated at the pole faces 22a and 22b and there is a minimumleakage ilux from the sides of the magnet 22 disposed adjacent theterminal pin 36. It should also be noted that the magneti-c terminal 36provides a lower reluctance path yfor the ux from the pole `face 22bthan a path entirely through air in spite of the air gap separating thepole face 22h and the upper portion of `the terminal 36 so that thelower end of the terminal 36 is magnetically biased to assume a polarityopposite to that of the lower end of the terminal pin 38. Accordingly,the upper end of the armature 32 is magnetically retained in engagementwith the lower end of the magnetic terminal 33 to provide thesingleside-stable construction.

When the sealed switch 18 is inserted into an axial opening in one ofthe windings 20, and the assembled switch units and windings 2i are theninserted into each of the openings 14 so that the terminal 34 ispositioned within the opening 26 with its lower end disposed within theopening 28. At the upper end of the sealed switch unit is placed in aposition resting on the a conductive segment 16 on one side of the panel12 while the other magnetic terminal 36 is disposed adjacent the loweror other surface of the panel 12 in a position laterally displaced fromalignment with the terminal 38. A single bias magnet 22 is then placedon each of the enlarged end portions 16C adjacent the upper ends of theopenings 14 (FIG. 1) with the magnetic axis of the magnet extendinggenerally parallel to the panel 12. The iiux iield of the permanentmagnet 22 holds this magnet in intimate engagement with the magneticterminal 38 in a proper position in which the side of the magnet 22 isspaced from the magnetic terminal 36 by the intervening dielectric panel12. In this position, the axis of the terminal pin 36 is intersected bya line extending perpendicular to the magnetic axis of the magnet 22.One or more panel 12, as by soldering these terminals to the adjacentportions 16e of the conductive segments 16. In addition, the permanentmagnet 22 can be soldered to the terminal pins 38 or the enlargedportions 16e or to both of these elements.

In certain instances, it may be desirable to solder the permanentmagnets 22 to the terminal pins 38 before assemblying the sealed switchunits 18 on the dielectric and biasing magnet 22 are positioned on theboard 12, the engagement of the side wall of the permanent magnet 22with the panel 12 aids in properly locating the terminals 36 and 38relative to the panel 12.

Although the permanent magnets 22 can be magnetized to provide magneticfields of suitable strength and orientation prior to` being mountedadjacent the magnetic terminals 38, this practice may not be desirablebecause of the possibility of a change in the selected magneticcharacteristics during the assemblying operation and because of the factthat the sealed switch units 18 may possess different operatingcharacteristics that must be compensated for by providing biasingmagnets of different iield intensities. Accordingly, it is preferable tomount unmagnetized magnetic material which is to form the permanentmagnet 22 in a proper position adjacent the magnetic terminal 38 and tothen subject the material to a magnetic field of sutlicient strength andthan is required to blas the sealed switch unit 18 forsingle-side-stable operation. This magnet is then subjected to analternating current eld which reduces the intensity of its magneticfield. During the application of the alternating current signals, testequipment connected to the sealed switch unit 18 indicates the operatingcharacteristic of the unit 18 so that a desired release or operatemargin can be established. When the desired operating characteristic isestablished, the application of the alternating current eld to thepermaof the field of the permanent magnet 22 can be adjusted in themanner described above to control the operate and releasecharacteristics of the sealed switch unit 18, the angular deilection ofthe permanent magnet about the axis of the magnetic terminal 38, thelength of the permanent magnet 22 in the direction of its magnetic axis,and the consequent spacing of the pole face 22b from the magneticterminal 36 can also be varied in order to control the operatingcharacteristics of the sealed switch unit 18.

If desired, the windings Ztl can be secured in proper positions on thedielectric panel 12 and this panel, the conductive segments 16, and theother components car ried on the board 12 can be electrically insulatedand protected from the atmosphere by bonding a pair of assembly 10.

In the normal condition of the switching assembly 10, the biasingmagnets 22 magnetically retain the magnetic armatures 32 in engagementwith the lower ends of the energizing signal is applied to one or ings2t) over the conductive segments 16 connected thereo develop ilux eldswhich induce a polarity ends of the magnetic armatures 32 that isopposite to the polarity of the lower ends of the terminals 38, theupper ends of the magnetic armatures 32 are repelled from the lower endsof the terminals 38 and are attracted toward the lower ends of theterminals 36 so that the armatures 32 engage the terminals 36 to openlthe break contacts and to close the make contacts. When theenergization of the coils 20` is terminated and the ux Vfields collapse,the intensity of the fields induced at the lower ends of the terminals38 and the resiliency of the armatures transfer the armatures 32 frompositions engaging the lower ends of the terminals 36 to ones in whichthese armatures engage the lower ends of the terminals 3S. Thus, themake contacts are opened and the break contacts are closed, and the aposition in which said magnetic axis extends .sealed switch units 1S arerestored to their normal condition.

Although the present invention has been described with reference to a-single illustrative embodiment thereof, it should be understood thatnumerous other modiiications and embodiments can be devised by thoseskilled Iin the art that will fall within the spirit and scope of theprinciples of this invention.

What is claimed and desired to be secured by Letters Patent of theUnited States is:

l. A switching unit comprising a sealed switch unit having a pair ofmagnetic terminals carried thereon, a permanent magnet having a pair ofspaced pole faces at opposite ends of a magnetic axis, and meansmounting said permanent magnet for magnetically biasing the two magneticterminals with fields of opposite polarity with one of said pole facesadjacent one of said magnetic terminals and with a straight lineconnecting said pole faces extending generally transverse to said oneterminal and outwardly at an acute angle from a line connecting saidmagnetic terminals so that the other pole face is spaced from the otherterminal to apply diiferent degrees of magnetic bias to the two magneticterminals.

2. A switching unit comprising a dielectric envelope, a pair ofgenerally parallel magnetic terminals spaced from each other by a givendistance, a permanent magnet having a pair of pole faces spaced fromeach other a distance along a magnetic axis of said permanent magnetthat is greater than said given distance, and means positioning saidpermanent magnet for magnetically biasing the two magnetic terminalswith iields of opposite polarity with one pole face adjacent one of saidterminals and with said magnetic axis extending toward said otherterminal at an acute angle relative to a line passing through both ofsaid terminals so that said other pole face is spaced from said otherterminal to apply different degrees of magnetic bias to the two magneticterminals,

Y3. A switching unit comprising a sealed dielectric envelope, a movablemagnetic armature in said envelope, a pair of magnetic terminals carriedon said envelope and including a lirst portion positioned adjacent oneend of said armature and a second portion disposed outside of saidenvelope, said magnetic armature having a portion disposed between thefirst portions of the pair of magnetic terminals and being free ofmechanical stresses sufficient to bias said armature into engagementwith either of said magnetic terminals, a permanent magnet having twopole faces positioned at opposite ends of a magnetic axis, and meanssecuring one pole face of said permanent magnet to one of said secondportions with said magnetic axis extending generally transverse to saidone second portion and forming an acute angle with a line passingthrough both of said second portions, said other pole face of saidpermanent magnet being spaced from said other second portion, the twoterminals being magnetically biased by said magnet with fields ofopposite polarity.

4. A switching unit comprising a sealed dielectric envelope, a pair ofmagnetic terminals carried on said envelope and extending along a pairof spaced parallel lines, a magnetic armature contained within saidenvelope and including a portion disposed between and movable relativeto said magnetic terminals, said magnetic armature being free ofmechanical stresses suicient to bias said portion into engagement witheither of said pair of magnetic terminals, a permanent magnet having apair of pole faces connected by a magnetic axis, and means mounting saidpermanent magnet for magnetically biasing the two magnetic terminalswith iields of opposite polarity with one pole face adjacent one of saidmagnetic terminals and spaced from the other of said magnetic terminals,said permanent magnet being mounted in generally transverse to the axisof said one magnetic terminal and in lwhich a line perpendicular to saidmagnetic axis in- 'tersectsthe axis of said other magnetic terminal.

5. A switching assembly comprising a dielectric panel having an opening,a sealed switch unit having a pair of spaced magnetic terminals, meansmounting said switch unit in said opening with the terminals disposed onopposite sides of said panel, a permanent magnet having a pair ofopposite pole faces at opposite ends of a magnetic axis, and meansmounting said permanent magnet on said panel for magnetically biasingthe two magnetic terminals with fields of opposite polarity with one ofsaid pole faces adjacent one of said terminals and with said magneticaxis extending substantially parallel to said panel.

6. A switching assembly comprising a dielectric panel having an openingtherein and at least one electrically conductive layer disposedadjacentan edge of said opening, a sealed switch unit having at least a pair ofspaced magnetic terminals at one end thereof, said sealed switch unitbeing positioned in said opening with one of said terminals secured tosaid layer on one side of said panel and with the other terminalpositioned on the other side of said panel, and a permanent magnetmounted adjacent one of said terminals and spaced from the other of saidterminals by said panel, with the two terminals magnetically biased bysaid magnet with elds of opposite polarity.

7 A switching assembly comprising a dielectric panel having an openingtherein and at least one electrically conductive layer on at least oneside of said panel disposed adjacent an edge of said opening, a sealedswitch unit having a pair of magnetic terminals at one end thereof, saidsealed switch unit being disposed in said opening with one of saidterminals engaging said layer on one side of said panel and the other ofsaid terminals positioned on the other side of said panel spacedlaterally from said one terminal, means connecting said one terminal tosaid layer, and a permanent magnet mounted on said one side of saidpanel adjacent said one terminal and extending over said other terminalbut spaced therefrom by said panel, with the two terminals magneticallybiased by said magnet with fields of opposite polarity.

8. A switching assembly comprising a dielectric panel having an opening,a sealed switch unit having a pair of generally parallel and spacedmagnetic terminals, said sealed switch unit being mounted in saidopening with one of said terminals positioned on one side of said paneland the other of said terminals positioned on the other side of saidpanel, a permanent magnet having a pair of pole faces connected by amagnetic axis, and means mounting said permanent magnet on said panelfor magnetically biasing the two magnetic terminals with fields ofopposite polarity with one of said pole faces adjacent one of saidterminals and so that a line perpendicular to said magnetic axisintersects the other of said terminals.

`9. A switching assembly comprising a dielectric panel having aplurality of spaced openings, a plurality of electrically conductivelayers secured to spaced portionsof said panel and including portionsdisposed adjacent said openings, a plurality of sealed switch units eachcomprising a dielectric envelope having at least two spaced terminals,each of said switch units being disposed in one of said openings withthe terminals secured to said portions, and ya winding disposed in eachof said openings and carried on the dielectric envelope of the sealedswitch unit, said openings generally conforming to the contiguration ofthe windings to locate said windings in proper positions on said sealedswitch units.

l0. A switching assembly comprising a dielectrical panel havingaplurality of spaced openings, a plurality of electrically conductivelayers secured to spaced portions of said panel and including portionsdisposed adjacent said openings, a plurality of sealed switch units eachcomprising a dielectric envelope having at least two spaced magneticterminals projecting from one end of said envelope, permanent magneticmeans secured to one of each pair of said terminals and disposedadjacent but spaced from the other one of the terminals in each pairthereof to magnetically bias the two terminals of each pair with fieldsof opposite polarity, each of said switch units being disposed in one ofsaid openings with at least one of the terminals secured to one of saidportions, and a winding disposed in each of said openings and carried onthe dielectric envelope of the sealed switch unit, said openingsgenerally conforming to the coniiguration of the windings to locate saidwindings in proper positions on said sealed switch units.

11. The switchingy assembly set forth in claim including a dielectricmaterial covering each side of said panel to electrically andmechanically protect said switching assembly and to electricallyinsulate said permanent magnetic means.

12. A switching assembly comprising a sealed and elongated dielectricenvelope, a pair of magnetic terminals carried on one end of saidenvelope and each including a first portion disposed within the envelopeand a second portion projecting out of said envelope, said secondportions extending generally parallel to each other and being spacedfrom each other a given distance, a movable magnetic armature supportedfrom the other end of said envelope and having a portion disposedbetween the first portions of the pair of magnetic terminals, saidmagnetic armature being free of mechanical stress suticient to bias saidarmature into engagement with either of said magnetic terminals,permanent magnet means having two pole faces of opposite polaritypositioned at opposite ends of a magnetic axis, the length of saidpermanent magnet means along a straight line connecting the pole facesbeing greater than said given distance, and means securing one pole faceof said permanent magnet means adjacent one of said second portions withsaid straight line extending transverse to said one second portion andforming an acute angle with a line passing through both of said secondportions so that the other pole face of said permanent magnet means isspaced from said other second portion, the two terminals beingmagnetically biased by said magnet with fields of opposite polarity.

13. A switching assembly comprising a dielectric panel having anelongated opening therein, at least one electrically conductive layerhaving a portion disposed adjacent one end of said opening, a sealedswitch unit including a pair of spaced magnetic terminals at one endthereof, said sealed switch being disposed in said opening with saidpair of magnetic terminals disposed with at least one of said pair ofmagnetic terminals disposed ad- Jiacent said portion of the electricallyconductive layer, means connecting said one magnetic terminal to theadjacent portion of the electrically conductive layer, and permanentmagnet means for biasing the two terminals of said pair with fields ofopposite polarity and including a pair or" opposite pole faces disposedat opposite ends of a magnetic axis, the length of Said permanent magnetmeans in the direction of said magnetic axis being greater than thedistance between said pair of magnetic terminals, said permanent magnetmeans being connected to one ot the magnetic terminals with one of thepole faces adjacent this terminal and with the other pole face spacedfrom the other magnetic terminal, the magnetic axis of said permanentmagnet means extending generally transverse to the connected one of themagnetic terminals and forming an acute angle with the plane passingthrough the pair of magnetic terminals.

References Cited in the file of this patent UNITED STATES PATENTS2,821,597 Germanton et al. Jan. 28, 1958 2,823,360 Jones Feb. 11, 19582,877,315 Oliver Mar. l0, 1959 2,898,422 Peek Aug. 4, 1959 2,907,846Wilhelm Oct. 6, 1959 2,922,857 Peek Jan. 26, 1960 2,929,895 ShebanowMar. 22, 1960 2,957,961 Juptner Oct. 25, 1960 2,999,915 Peiderer et alSept. 12, 1961 3,002,067 Baldwin et al. Sept. 26, 1961

1. A SWITCHING UNIT COMPRISING A SEALED SWITCH UNIT HAVING A PAIR OFMAGNETIC TERMINALS CARRIED THEREON, A PERMANENT MAGNET HAVING A PAIR OFSPACED POLE FACES AT OPPOSITE ENDS OF A MAGNETIC AXIS, AND MEANSMOUNTING SAID PERMANENT MAGNET FOR MAGNETICALLY BIASING THE TWO MAGNETICTERMINALS WITH FIELDS OF OPPOSITE POLARITY WITH ONE OF SAID POLE FACESADJACENT ONE OF SAID MAGNETIC TERMINALS AND WITH A STRAIGHT LINECONNECTING SAID POLE FACES EXTENDING GENERALLY TRANSVERSE TO SAID ONETERMINAL AND OUTWARDLY AT AN ACUTE ANGLE FROM A LINE CONNECTING SAIDMAGNETIC TERMINALS SO THAT THE OTHER POLE FACE IS SPACED FROM THE OTHERTERMINAL TO APPLY DIFFERENT DEGREES OF MAGNETIC BIAS TO THE TWO MAGNETICTERMINALS.